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A recommended vision standard for police officers is presented. The visual capabilities needed to perform various police duties are described. A specific vision standard, along with criteria for screening referral or screening failure are given for each category of visual skills required for police work.
AIM: To evaluate whether previous isotretinoin use induces permanent, measurable, and clinically significant abnormalities in night vision such that flying is precluded, and whether potential military and civilian commercial aviators should be screened routinely. METHODS: A retrospective, non-interventional, consecutive case series of 47 individuals with a confirmed history of oral isotretinoin use were compared to 20 age and sex matched controls. RESULTS: 47 individuals (44 males and three females), age range 17-33, underwent Goldmann-Weekers dark adaptation (DA) and standard electroretinogram (ERG) according to ISCEV protocols. 34 patients showed no abnormality in any parameters. Two patients had abnormal DA and ERGs. The mean scotopic ERG b wave amplitude of the isotretinoin group was 496.5 microV (SD 51.3 microV) compared with 501.7 microV (62.3.1 microV) among the controls. The group mean a:b ratio was 0.55 (0.04) compared to 0.69 (0.08) in the controls. CONCLUSION: Previous use of isotretinoin may have caused retinal toxicity in two subjects and laboratory evidence of night blindness in 11 further subjects. One subject had subclinical changes remaining in the ERG 96 months after cessation of isotretinoin. This may justify the directed use of electrophysiological screening in professions that are night vision critical.
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CONTEXT: Existing guidelines recommended by the Canadian Pediatric Society (CPS) and American Academy of Pediatrics (AAP) for routine screening for retinopathy of prematurity (ROP) remain controversial. OBJECTIVE: To determine whether current guidelines for routine screening for ROP should be changed. DESIGN: We examined data that were collected as part of a larger study of 14 neonatal intensive care units (NICUs) in Canada. We examined the effect of strategies using different birth weight (BW) and gestational age (GA) criteria for routine ROP screening, and performed a cost-effectiveness analysis. SETTING: The 14 NICUs (except one) are regional tertiary level referral centres serving geographic regions of Canada, and include approximately 60% of all tertiary-level NICU beds in Canada. PATIENTS: This large cohort included all 16 424 infants admitted to 14 Canadian NICUs from January 8, 1996, to October 31, 1997. INTERVENTIONS: None. MAIN OUTCOME MEASURE: Treatment for ROP. RESULTS: The most cost-effective strategy was to routinely screen only infants having a BW of 1200 g or less. This included all infants treated for ROP (except 1 outlier at 32 weeks GA and 1785 g BW), at a marginal cost per additional person with improved vision of $513 081 for screening patients between 28 weeks GA and 1200 g BW, compared with $1 800 039 and $2 075 874 for using the current AAP and CPS guidelines, respectively (cryotherapy outcomes). Results for laser therapy were similar, but costs were slightly lower. This strategy reduced the number of infants screened under the current CPS guidelines by 46%. CONCLUSION: Screening only infants having a BW of 1200 g or less is the most cost-effective strategy for routine ROP screening.
OBJECTIVE: To establish a three-level eye care network, together with a referral and monitor system for the prevention of blindness, with the aim of creating a cataract free zone. SUBJECTS AND METHODS: Shunyi County with a population of 548364 was chosen as the target site. Our activities included (1) establishment of a County Guiding Committee for the prevention of blindness: (2) training local ophthalmologists and primary eye care personnel: (3) extensive publicity of knowledge for the prevention of blindness: (4) screening for blindness and low vision, (5) cataract surgery as the chief measure for creating a cataract free zone. RESULTS: A referral and monitor system for cataract blindness was established in 1987. Seven local ophthalmologists, 449 primary eye care health workers and six optometrists were trained. 815 cataract-blind patients were identified. Up to December 1991, 667 patients (737 eyes), accounting for 81.84% of the total, were treated with cataract surgery, 90.64% of these eyes had their sight restored, and 59.66% patients resumed work. A cataract free zone has been created in Shunyi County. CONCLUSIONS: The prevention of blindness with cataract surgery as the chief measure can dramatically decrease the prevalence of blindness in a relatively short period of time.
BACKGROUND: Aniridia typically appears as a familial condition with autosomal dominant inheritance but can present as an isolated disease or sporadically in association with several syndromes. In this report we describe the various ocular manifestations of aniridia as well as the association of familial aniridia with two different ocular and systemic abnormalities present across three generations in two different families. METHODS: Descriptive case series of 33 patients (66 eyes) with aniridia. A full eye examination was performed at the beginning of the study, including past medical history, family history and type of inheritance, assessment for fixation pattern and presence of nystagmus, visual acuity testing, refraction, slit-lamp examination, gonioscopy, fundus examination with pupil dilation and anterior segment photography; additional glaucoma testing was done if the patient had high intraocular pressure. Patients were followed for at least 2 years. The interval between follow-up visits, which included gonioscopy and fundus examination with pupil dilation, depended on the findings in each case. A urology consultation was requested in all sporadic aniridia cases; consultations in psychiatry and gynecology were requested on the basis of the medical history or clinical suspicion during the ophthalmologic examination. RESULTS: Ten patients (30%) had sporadic aniridia, with no previous family history; Wilms' tumour did not develop in any of them during the follow-up period. In the autosomal dominant group, ocular and systemic findings present in combination with aniridia were observed in 20 patients in the two families. Family I had aniridia and developmental delay or behavioural disorders in three generations as well as high myopia (greater than 6.00 dioptres) in all affected adults. Family 2 presented a wide phenotypic variability of aniridia with myopia in three generations. Open-angle glaucoma developed in three young adults in this family, and two members were found to have gynecologic abnormalities (hypoplastic uterus and imperforate vagina). Myopia was the most prevalent refractive error (64%) in the 33 patients. Refractive correction significantly improved the visual acuity in half of these cases. Glaucoma was present in 10 patients (30%) and was the main cause of vision loss, provoking blindness in two cases (6%). Affected patients manifested progressive angle closure or presented with open-angle glaucoma. INTERPRETATION: Ophthalmologists should consider aniridia in patients with unusual iris malformations. Examination of family members may be key in making the diagnosis. Any refractive error should be corrected, as this may improve vision. All aniridic patients should be screened regularly for glaucoma, as this condition may occur at any age and can lead to permanent vision loss. Systemic and ocular associations should be considered as they may present in combination with anirida. In our series, developmental delay or behavioural disorders and myopia were associated conditions.
BACKGROUND: Type II diabetes mellitus is a major health problem among Native Americans, and diabetic retinopathy is a frequent complication of this disease. Screening for retinopathy can identify early disease and prevent major vision loss, but the most cost-effective screening method has not yet been determined. METHODS: In a rural clinic that served more than 400 Native Americans with diabetes, we compared the accuracy of referrals made based on two screening methods: ophthalmoscopy by trained primary care physicians and seven-view nonstereoscopic, mydriatic fundal photography read by two general ophthalmologists and a retinal specialist. Patients in whom abnormal findings were detected by either screening method were then referred to a general ophthalmologist for further evaluation. RESULTS: Two hundred forty-three examinations were performed and 83 referrals made. Both screening methods had high sensitivity for referring patients with retinopathy that required treatment or follow-up sooner than 1 year (100% for direct ophthalmoscopy by primary care physicians, 94% for the general ophthalmologist photography readers, and 100% for the retinal specialist reader). The calculated costs of screening by direct ophthalmoscopy and by retinal photography were 64% less and 44% to 35% less, respectively, than the cost of yearly ophthalmological examinations by ophthalmologists. CONCLUSIONS: Careful screening for treatable diabetic eye disease by trained primary care physicians proved to be a clinically acceptable, cost-effective strategy. Screening methods for diabetic retinopathy should be evaluated based on the absolute sensitivity, specificity, and predictive values of their ability to correctly refer patients rather than their diagnostic accuracy.
A commonly used method of investigating colour vision, that is, the ability of the human visual system to discriminate colours, is based on the use of isochromatic colour plates, such as those used in the Ishihara test. The present paper describes a new computer-based method of determining red/green colour vision deficiencies. The method involves the presentation of Ishihara colour plates on a computer monitor. It has been verified experimentally that, despite the differences between the spectral emission of the computer screen and the daylight reflected by the Ishihara plates, the method is capable of distinguishing between subjects with from those without colour vision deficiencies. For screening purposes, the use of a reduced number of plates is suggested. This suggestion makes use of nine instead of 14 plates, and the criterion of two incorrectly recognized plates to determine a colour vision deficiency.
Testing of visual acuity for distant vision can be computerized by using monitor screens to present optotypes. Because of the limited spatial resolution of conventional monitors, measurement of visual acuity for near vision is not possible. This paper describes a new computer-aided method for the measurement of both near and distant visual acuity. Our approach to the assessment of visual acuity for near vision is based on a recently developed liquid crystal display (a screen, LCD) measuring 10.5 mm x 15 mm. The LCD permits the presentation of optotypes for the measurement of visual acuity between 0.063 and 1.25 at a viewing distance of 40 cm (near/distant). The presentation of optotypes for the assessment of the acuity of distant vision uses a standard 17" monitor that permits visual acuity figures of between 0.032 and 1.6 to be assessed.
Ensuring that our forces are vision ready, i.e., they have the appropriate visual acuity, optical devices, and eye health to perform their mission, is essential on today's battlefield. A study was conducted at Seymour Johnson Air Force Base to determine the prevalence of vision readiness in a deploying fighter squadron. Of the 204 personnel screened, 59 wore glasses or contact lenses. Of these 59, 15 individuals (25%) were optically ready and 44 individuals (75%) were not optically ready to deploy. Optical readiness is defined as having the correct type and number of optical devices. Of the 15 individuals (25%) who were optically ready, 13 (87%) had had a professional eye examination within 12 months. Of the 44 individuals (75%) who were not optically ready, 36 (82%) had been examined within 1 year. Pearson's chi 2 test (chi 2 = 1.59, degrees of freedom = 3, significance = 0.66) indicated that there was no significant association between readiness and the date of the last examination. This study reveals that although personnel are having regular periodic professional eye examinations, optometry personnel, commanders, and deploying airmen must take a more active role in ensuring that our forces are vision ready.
BACKGROUND: The Color Vision Meter 712 (CVM) is a new automatic computerized anomaloscope relying on both the Rayleigh and the Moreland equation. In the present study the diagnostic value of Color Vision Meter was examined in glaucoma for the first time and was compared with the Farnsworth 100 hue test. PATIENTS AND METHODS: 33 normals, 15 patients with ocular hypertension (OHT) and a heterogenic group of 31 glaucoma patients were tested with the Nagel anomaloscope, the Color Vision Meter 712 and the Farnsworth 100 hue test. The following determinations were made in all subjects: 1. Anomalous quotient of the Rayleigh equation of the Nagel anomaloscope and of the Color Vision Meter, 2. Mean tritan score of 100 hue test, 3. The matching range, mid matching point, and anomalous quotient of the Moreland equation with the Color Vision Meter. RESULTS: While in the OHT group only the matching range of the Moreland equation was enlarged, all three variables (matching range, mid matching point and anomalous quotient) of the Moreland equation were significantly changed in the glaucoma group. The mean tritan score of the 100 hue test showed in the OHT group only a slight difference compared to normals, and in the glaucoma group a low significance and a low sensitivity. The matching range of the Moreland equation seems to be most useful with a sensitivity of 87.1% and a specificity of 93.6%. CONCLUSION: Our results show that the new anomaloscope Color Vision Meter 712 should be considered as a quick screening test for the examination of blue-color vision disturbances in glaucoma because of its higher sensitivity, its easier use for examiner and patients, and its shortened examination time (5 min per equation).
Early detection and timely treatment of diabetic retinopathy can preserve vision, yet many people with diabetes do not have their eyes examined regularly. The purpose of this study was to examine eye care practices of people with diabetes who had not previously accessed eye care services on a regular basis. Screening with non-mydriatic retinal photography for diabetic retinopathy was initiated in 1996, and targeted people with diabetes who did not access eye care services on a regular basis. Each test area was revisited 2 years after the initial screening. Patients that did not attend the biennial screening were followed up by mail survey. Although none of the participants in this study had been previously accessing eye care services on a regular basis, 87% did so after attending the screening. These results indicate that mobile screening with non-mydriatic photography, as an adjunct to current eye care services, has the potential to increase examination compliance for diabetic retinopathy and to achieve sustained behaviour change.
The apposition compound eyes of mantis shrimps (stomatopods) are divided into three sections, the dorsal and ventral hemispheres and the midband. Many ommatidia of both hemispheres, and all those in the midband, sample the same narrow band in space. The function of the morphologically distinct midband region is not clear, but new evidence suggests that it may be adapted in a unique manner for colour and polarization vision. A series of carotenoid colour filters screen the photopigment and potentially provide a tetrachromatic input for contrast-enhanced vision or true colour vision. The filters are blocks of coloured droplets (red, orange, yellow, purple, pink or blue) within the rhabdoms of two rows of midband ommatidia. The arrangement of tiered microvilli in two other midband rows suggests that they provide a unique form of polarization vision.
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Analyzing cerebral asymmetries in various species helps in understanding brain organization. The left and right sides of the brain (lateralization) are involved in different cognitive and sensory functions. This study focuses on dolphin visual lateralization as expressed by spontaneous eye preference when performing a complex cognitive task; we examine lateralization when processing different visual stimuli displayed on an underwater touch-screen (two-dimensional figures, three-dimensional figures and dolphin/human video sequences). Three female bottlenose dolphins (Tursiops truncatus) were submitted to a 2-, 3- or 4-, choice visual/auditory discrimination problem, without any food reward: the subjects had to correctly match visual and acoustic stimuli together. In order to visualize and to touch the underwater target, the dolphins had to come close to the touch-screen and to position themselves using monocular vision (left or right eye) and/or binocular naso-ventral vision. The results showed an ability to associate simple visual forms and auditory information using an underwater touch-screen. Moreover, the subjects showed a spontaneous tendency to use monocular vision. Contrary to previous findings, our results did not clearly demonstrate right eye preference in spontaneous choice. However, the individuals' scores of correct answers were correlated with right eye vision, demonstrating the advantage of this visual field in visual information processing and suggesting a left hemispheric dominance. We also demonstrated that the nature of the presented visual stimulus does not seem to have any influence on the animals' monocular vision choice.
PURPOSE: To evaluate the long-term outcome of a cohort of people with diabetes screened by the Exeter Diabetic Retinopathy Screening Programme. METHOD: The cohort comprised of diabetic patients from nine market town General Practices around Exeter who first attended the diabetic retinopathy screening programme in 1992. Screening was carried out by a combination of dilated fundoscopy by a screening technician and a single 45 degrees Polaroid photograph of each eye. The prevalence of diabetic retinopathy at the baseline, the incidence of sight threatening diabetic retinopathy (STDR) in the next two rounds of screenings, and the long-term visual outcome are described. RESULTS: The cohort consisted of 775 patients (104 Type I, 517 Type II non-insulin-requiring and 154 Type II insulin-requiring). The mean age was 72.1 years (15-100), with mean disease duration of 13.0 years (1-79). Baseline prevalence was as follows: background retinopathy: 21.4%, proliferative: 2.8%, clinically significant macular oedema: 6.1%. The incidence of proliferative disease was 2.20% and 2.25% respectively in the next two rounds of screening (P > 0.05, chi2 test). The incidence of clinically significant macular oedema was also constant over next two rounds of screening, at 4.79% and 5.18% respectively (P > 0.05, chi2 test). Ninety-five (12.3%) patients were deceased and a further 179 (23%) patients were lost to follow-up by the third round. Only two patients with newly diagnosed STDR suffered deterioration of visual acuity to 6/60 or worse as a result of diabetic retinopathy. CONCLUSION: The incidence of STDR remained constant throughout the period of screening, reflecting the chronic progressive nature of the disease. Significant numbers of patients were lost to follow-up. Screening seemed effective in preserving vision in those patients with newly diagnosed STDR.
Evoked potentials (EP's) in response to phase-alternating gratings were recorded from normal and stereoblind or stereodefective subjects (adults and children) under monocular and binocular viewing conditions. The amplitude of the binocular EP was found to exceed the larger monocular EP in normal but not in stereodefective subjects, no matter whether the amplitudes of the two monocular EP's were the same or not. This finding provides an objective method for screening out defects of binocular vision. EP's recorded from a group of infants 2 to 18 months old suggest that a larger amplitude of the binocular EP, as compared with the monocular EP's, is the norm even in the earliest period of life.
There are many advantages to the computerization of colour vision tests. However, previous computerized colour vision tests have involved equipment and methods not commonly used in clinical practice. We created computer emulations of the City University Colour Vision Test (CUT), Ishihara plates and American Optical Hardy-Rand-Rittler (AO-HRR) plates using a commonly available 24-bit colour Macintosh computer. Our colour monitor was calibrated to standard display white (D65), and colour plates were imaged with a colour scanner. The computerized colour images were compared with the standard test plates in a sample of 21 subjects with normal colour vision, 10 patients with congenital red-green defect and 1 patient with an acquired mixed colour defect. The computer images of the three tests correlated well with their conventional counterparts on kappa statistic analysis (p < 0.001), for both the colour normal and colour defective groups. We conclude that our computer emulations of the CUT, Ishihara and AO-HRR tests screen subjects with normal colour vision with high specificity and delineate congenital colour defects with a sensitivity comparable to that of their conventional counterparts.